Yarn / needle

Yarn / needle chart

This tool helps you to decide which needle size to use for a given yarn and to estimate the resultant fabric gauge (stitches per 10cm).

Although modern yarns are labelled with this information, often we have old or unlabelled yarn that we would like to use.

The Craft Yarn Council's standard yarn weight system chart provides a general guide, which may be helpful.

I have created the diagram below using actual yarn data from three manufacturers: Rowan, Patons and Sirdar. Each yarn is sorted according to its 'count' - the length in metres per one gram of yarn. The count of a labelled yarn can be calculated from its weight and length - instructions are below the chart.

The yarns are sorted into two groups: cotton/silk and wool/acrylic. The right hand side of the chart relates gauge to needle size, using the same source data. 

To use the chart: take an unlabelled yarn, guess its yarn group and trace up and across from that group on the graph to get an idea of the likely gauge and a good needle size to try.

If you want to match the gauge of an existing fabric, look up the stitches per 10cm in the y axis and trace across to see the approximate count of yarn and needle size required.

The chart is available to download at the bottom of the page, along with the source data - so you can look up, for example, all currently available yarns with a specific recommended gauge.

Yarn count

To find the resultant new metric count (Nm) of any yarn:

length (m) ÷ weight (g) = count (e.g. a 50g ball of yarn that is 128m long: 128 ÷ 50 = 2.56 Nm)

For industrial yarns:

The new metric count will be written as number of plies, then the count of each ply (e.g. 2 / 28 Nm)

To get the resultant new metric count, calculate:

count of each ply ÷ number of plies = resultant count (e.g.  28 ÷ 2 = 14 Nm)

Note: an interactive version of this calculation is included in the 'interactive gauge change tool' spreadsheet, available to download on the gauge change page. 

Interactive yarn tool

Before I constructed the yarn / needle chart above, I made a spreadsheet tool which worked with similar data in a different way.

With this tool, you put in your desired gauge (stitches per 10cm) and it suggests an appropriate yarn type and needle size. (It does this using data I gathered from various online sources which gave generalised figures for needle size, fabric gauge and yarn count.)

Download interactive yarn tool Excel file (download begins immediately)